Evapotranspiration Changes Driven by Soil Moisture are Misrepresented in Climate Models

Evapotranspiration ( ET ) connects the terrestrial and atmospheric branches of the water and energy cycles. Soil moisture ( SM ) is typically considered a primary factor influencing ET. However, in a changing climate, isolating the role of SM as an ET driver is difficult due to concurrent changes in energy availability, atmospheric states, land use, and vegetation. Here, we introduce an empirical approach that apportions ET changes into two mechanistic pathways: a SM -driven pathway and a non- SM -driven pathway. Our analysis of remote-sensing-based data reveals that many regions experienced substantial ET changes in the early 21 ^st century, with most reductions attributed to the SM -driven pathway, while some modest increases are primarily driven by the other pathway. Historical simulations of climate models generally capture the non- SM -driven changes but do not reproduce the SM -driven changes correctly. Improving model representation of SM influences on ET change is thus essential for credible projections of future terrestrial hydroclimate.